How does cavity wall insulation work

Is cavity wall insulation ever worth installing? Does it work? Does it always cause a problem? Cavity insulation is really effective, reduces energy consumption, makes homes warmer, cosier and cheaper to run…most of the time. The way heat moves means that if your room is warm but it is cold outside, heat will move through the wall, cooling the room until a balance is reached — in effect the room becomes as cold as outside!

I am so confused and nedd to make a decision. I will have to borrow money for external wall insulation but dont mind as long as this is the right thing to do and will save me money on bills and keeep housr warm. Please help. Explain in details. That makes cavity walls a bit more efficient that solid walls and therefore as such have a marginally smaller u-value.

Sorry about putting this in as a plug, but as you have talked about PAYING for wall cavity insulation I thought I should point out you can have this installation for free.

Hi, I was wondering if you could provide me with some assistance. We had someone knock on the door offering free cavity wall insulation.

It is not something I had considered previously, but since it is free I thought I would do some research. I live in Leicester about the most famous place on the planet after the football this weekend!! So how do I know if my property is suitable? It is semidetached and from I have asked my neighbours either side and one has had it done and one has refused so far.

Any thoughts on whether I should get cavity wall insulation would be greatly appreciated! Hi Lisa, where abouts are you based? Cavity wall insulation when installed correctly is a brilliant energy saving solution — however there are cases where it is not worth installing cavity wall insulation and solid wall insulation should be installed instead on the cavity walls.

Solid wall insulation prevents winter ingress, so if you live in areas of driving rain this is the preferable solution. Hi Susan, a very interesting comment and I would of thought a sentiment shared by many — is cavity wall insulation safe to install on my home? Well the answer really depends as the research you have carried out suggests. In many cases cavity wall insulation is incredibly effective energy saving measure — again as you mentioned there are companies still offering this for free and the impact on energy bills can be huge.

As such, filling the cavity with insulation could make pathways across the cavity by which water can pass from the outer leaf to the inner leaf. Nowadays though the cavity definitely has two functions — the first is to prevent water crossing the wall structure but also the cavity is used to house insulation.

I think it comes down to a few simple things — firstly it is important the right insulation product is used wool or blown beads.

If you have a property at the top of a hill or on the West coast then cavity wall insulation should also be avoided because of the risk of driving rain. Also and this is the hardest to judge not all cavity wall installers are great at what they do. If the cavity is not filled correctly then it will lead to cold spots in the house, also there are companies that inject the cavities and fill flues and vents which obviously should not be filled.

I would always try to get a recommendation so speak to previous customers that the cavity wall installer has used — sorry to not be any more help! Hi, I live in a semi built in When built, can you tell me if the cavity would normally flow through to next door or would it have been blocked where the two properties join? Hi, they normally will put down cavity brushes into the cavity where there is a risk of the insulation flowing down into adjacent properties. This ensures the cavity wall insulation stays exactly where required.

Hello, i have recently bough a timber frame house, in newcastle as is around 35 years old, however when i bought the property they had removed the cavity insulation because they had to certoficates, should i be looking at getting it reinstalled? I understand that a dofferent type of jInsulatoon is required for this build type. Also if i have jt done would i Also be fIlling my Neigblurs walls?

Mid terrace thanks. Hi Phillip, there are currently no cavity wall insulation materials suitable for timber frame properties hence the need to remove it from your property. We have heard there is going to be a material released soon that is suitable but this is still going through final testing, but hopefully it will be released at some point during The assessor predicted it was under 45mm, so I am not sure what the potential energy savings would be but also I am aware that cavity wall insulation in some cases can cause damp, although we are located in near Reading and from what I have heard damp often happens in areas of high exposure.

If we did end up insulating the cavity what is the product that offers the best thermal performance. Hi Jimmy, my thoughts are that yes — regardless of the depth of the cavity, some insulation is better than none! In terms of cavity wall insulation failure rate, the numbers are actually pretty small and as you correctly point out, the failures tend to be far more concentrated in high exposure areas. For narrow cavities we would recommend going for the EPS beads bonded , as these offer really good thermal insulation for the thickness compared to wool insulation products.

It also creates a barrier, preventing water cross from the outer skin to the inner skin of brick so I would recommend looking to that as your best bet. I am interested in getting cavity wall insulation installed on my s semi detached house. The house is generally cold so I am looking for a cost effective way of improving this situation! I have been trying to research cavity wall insulation online, but specifically I am trying to find out which of the insulation products is the best to get installed in the cavity, From what I have read I have 3 options, foam, wool or EPS beads.

Please can you let me know which is the best product to go for in terms of stopping damp entering but also providing the best level of insulation in the house. Would appreciate any help! Hi Applemaid, we would always suggest bead to be honest, you will pay slightly more than you would for wool, but it produces a waterproof barrier within the cavity, so water cannot travel through it which means there is no danger of getting damp in the home.

In addition this type of insulation has higher insulating properties than wool so therefore in our opinion it is the winner! I have a question regarding cavity wall insulation. We have been offered two types of free cavity wall insulation for our s mid terrace property.

The first is a bead, and the other is wool, both of which are injected. My question is pretty simple really, which one should I go for! I have read some horror stories about cavity wall; insulation, but my neighbours on either side have both had it done so I am happy that we are not in an area where the insulation would pose a risk on my home.

I guess since the insulation is hidden there are two things that are going to impact me, firstly the energy savings. I want to maximise these cause why not! Secondly, I want to minimise the risks associated with cavity wall insulation which as far as I can see is damp. So which will save me more and which is better at stopping damp crossing the cavity? Hopefully the answer to both of these questions is the same material!! I was wondering how does cavity wall insulation compare with external wall insulation from a u value rating?

Hi Jonathan, this depends on the thickness of the cavity as this limits the amount of insulation that can be used.

If you are insulating externally, you tend to use a minimum of 90mm of EPS expanded polystyrene. This will take the u-value of the solid wall down to 0. Over the years the cavity on cavity walls has been made thicker and thicker since its function moved from just preventing water ingress to doing that as well as housing insulation, but older cavities tend to be anywhere from 40mm — 60mm.

If you insulate the cavity with EPS beads, you should expect to achieve a u-value of 0. Basically solid wall insulation is better in terms of energy saving, because the amount of insulation you can add is unlimited. The issue is that solid wall insulation is far more expensive than cavity wall insulation. I want to get free cavity wall insulation and have heard there are government grants now available.

Is this the case? If you head over to our installer map, most sadly not all have access to this grant so put in your postcode to find your closest installer and then give them a call! Click here to head to our map!

We are interested in getting cavity wall insulation in our block of flats. Is there a grant to help cover the cost of this? It also gets extremely cold in the winter suggesting their is no cavity wall insulation. Will companies charge for an inspection to determine whether we can get this done. Similarly ventilators at ground level that ventilate below timber floors must be safeguarded.

The Technician will investigate them to check they are already sleeved. If they are not, the Technician will remove them and seal around them to stop them being blocked by the insulation.

Other vents, which may be redundant, such a cavity vents or vents that used to supply air to open fires in bedrooms may be closed off. The Technician should discuss these with you. Redundant airbricks may be filled. Yes — if your heating is not controlled by a thermostat. However, if you have a thermostat, it will cut out the heating at the same temperature, so you may not notice the difference in the room with the thermostat.

However, you should find that the temperature in other parts of your house improves, for example, the small bedroom on the corner. With CWI, you should find that the house holds its temperature for longer, therefore the time between heating cycles may be longer. Talk to the installing firm and tell them of your worries. A contract exists between you and the installer, so they must be given the opportunity to investigate your worries.

Read More ». As much as a third of the heat you pay for could be escaping through your roof. It's an easy way to save money. Draught proofing is one of the most inexpensive and effective energy efficiency measures for the home. These pockets are more efficient at reducing heat transfer by convection than the big air cavity was. They make it impossible for large convection currents to be set up.

They greatly reduce what is known as your walls' U value - which is a measure of how quickly they lose heat - from around 1. The lower the U value, the slower heat transfer - and the less energy you need to keep your home warm. Heat transfer by convection is reduced by making the air pockets very tiny - reducing the size of convection currents.